Earthmen and Earthwomen would be moving out en masse now to the new and virgin fields of endeavor -- to the farms of Venus, to the manufacturing centers that were springing up on Mars, to the mines of the Jovian worlds, to the great laboratory plants that would spring up on Titan and on Pluto and on the other colder worlds.

An all-male planet (name unspecified, but it has three ring systems, like an atom with electrons in three orbits) with a population of 4 million and led by Graydon (Ben Kingsley), decides it wishes to take over Earth by breeding with Earthwomen.

I’d also said that they would look nothing like the aliens of the movies, and that they would not have come to A) kill us, B) take over our planet and enslave us, C) save us from ourselves à la The Day the Earth Stood Still, or D) have sex with Earthwomen.

(The low population of Graydon's planet also makes it a problem in that even if every man on the planet impregnated 100 Earthwomen, there would still be only slightly over 400,000,000 descendants of the invaders and they would almost certainly be absorbed by the human race, especially since they look just like Earth men.